RF power sources for accelerators have been traditionally based on a variety of technologies including triodes, tetrodes, klystrons, IOTs, and solid-state amplifiers. The first four are vacuum tube amplifiers; a technology that has been the prime source for powers exceeding hundreds or even thousands of watts. Solid-state has become a strong competitor to power amplifiers in the kilowatt(s) power level up to 1 GHz. All of these technologies have a significant cost that can range from $5-$25 per watt of output power. These same technologies have AC to RF power efficiency potential of close to 60% in continuous wave saturated operation. These technologies are expensive and are relatively inefficient.
Magnetrons are another vacuum tube technology. Unlike the other devices listed, magnetrons are oscillators, not an amplifier. Magnetrons are the devices used in kitchen microwave ovens, industrial heating systems, and military radar applications. The attractive parameter of magnetrons in the particle accelerator field is the cost per watt of output power. The cost of a garden variety 1 kW magnetron one might find in their kitchen is under $10. There are simple, ready to use magnetron ovens available at under $100 at this power level. Industrial 80 kW continuous wave (CW) heating magnetron sources at 915 MHz are commercially available for $75 K.
Another benefit of magnetrons is their efficiency. While alternative technologies approach 60% efficiency at saturated power output, industrial magnetrons routinely operate at the 70% to 80% efficiency level. This improved efficiency can considerably reduce the operating electricity cost over the life of an accelerator.
However, for particle accelerator applications, a high degree of vector control is essential to achieve the required stable accelerating gradient. Therefore, a need exists for a magnetron that can provide an output that is essentially a saturated value for the given voltage and current applied to the device. The present invention includes injection locking means used to provide a very stable output phase and provides high dynamic range control of the amplitude with additional signal conditioning as disclosed herein.